Take The Weight-Loss Challenge

These four runners are stepping up to the starting line, ready to change their lives and lose weight for good. Are you?

Losing weight isn't just about looking good. For the four runners featured here, dropping pounds is a way to ward off health problems, end years of yo-yo dieting, boost confidence, and, well, run faster. With the help of a team of nutritionists and coaches, we've put together all the information you need to lose anywhere from five to more than 25 pounds. These four runners are stepping up to the starting line, ready to change their lives and lose weight for good. Are you?

She's had some success with the Atkins and South Beach diets, but for Kate Sanders, losing weight and keeping it off has been a constant struggle. The event planner knows the basics of nutrition and training from poring over books and magazines, but something still isn't clicking. "I try not to eat too many processed foods, I don't eat fast food, and I eat as many fruits and veggies as I can, but I can't get below 163," she says. Sanders, who started running in 2000, is currently logging about 15 miles a week before she begins preparation for her next half-marathon. "I realize I'll never be an Olympic athlete," she says. "But I do have the power to be fit for the rest of my life."

Starting weight: 170Target weight: 140Racing goal: To run July's Napa-to-Sonoma Wine Country Half-Marathon in less than two hours, beating her best time by 22 minutes

With two sets of twins (ages 8 and 3), a three-hour round-trip commute to New York City, and a job as an accountant that demands 10-hour days, Jim Dolan has his plate full. But he knows keeping his weight down is imperative; his family history includes heart disease, diabetes, and cancer, and he's on statins for high cholesterol. So three days a week, Dolan takes a 5:13 a.m. train to run on a treadmill before work. It's no surprise, though, that his nonstop lifestyle doesn't lend itself to good eating habits. "The people at McDonald's by my office know me by name," laughs Dolan, a six-time marathoner with a PR of 4:06. Yet he realizes he needs to kick those habits for his kids. "As much as I want to run Boston, I have the bigger picture of living a healthy, long life in mind," he says.

Laura DavisWants to lose: 15 poundsReason: Boost confidence and become a dedicated runner

A beginning runner who uses a run-walk method, Laura Davis was pleased about finishing her first half-marathon last spring. "I trained with a group and made some great friends," says the physician's assistant. "Plus, I experienced the runner's high and got in great shape." Problem is, the pounds she took off in training crept back on when nothing else was on the horizon. Her less-than-stellar diet doesn't help either. (She drinks coffee at 8 a.m., then doesn't eat until around 2 p.m.) While she's motivated to take on another half, Davis, like many beginners, lacks confidence in her abilities. Still, she's tasted what life is like with running as an essential part of the day and wants more. "I'm ready for that lifestyle change," she says.

Starting weight: 175Target weight: 160Racing goal: To run May's Flying Pig Half-Marathon in Cincinnati in less than 2:30, beating her PR by more than 30 minutes

Don't hate Ed Tam because he's fast. At the 2007 Philadelphia Marathon--his first 26.2--he clocked a 3:09:40, capturing a Boston qualifier. Even more enviable: The financial analyst followed a plan that included no speedwork and averaged three to four days of training a week. Looking forward to Boston, Tam wants to be like pro-cyclist-turned-marathoner Lance Armstrong. "Lance shaved almost 13 minutes off his second marathon by training harder and losing weight," says Tam. "I think if I employ a similar strategy, I can sneak in under three hours." Potentially holding Tam back are 60-hour work weeks, a love of anything that involves the words pizza or beer, and less than seven hours of sleep nightly. "I realize my goal is ambitious," says Tam, "but I think it's possible."

Starting weight: 168Target weight: 160Racing goal: To run a sub-three-hour Boston Marathon in April

Ed's Coaches:>Matt Russ, head coach and owner of The Sport Factory in Atlanta (sportfactory)>>Amy Bragg, R.D., L.D., director of performance nutrition at Texas A & M University Athletics in College Station, Texas (teamnutritioncoach.com)